This invention relates to correlation techniques.
In known correlation techniques, a reference image is compared with an image of a viewed scene, the reference image containing an object of interest, for example, a target, which is to be detected within the viewed scene. The reference image is scanned across the image of the viewed scene, and each pixel pair, ie one in the reference image and one in the viewed scene, is compared either by subtraction, multiplication or a more complex operator for each reference image position to form a correlation surface or array. However, these techniques may be sensitive to the presence of bright spots within the viewed scene which are due to external sources and thus may not provide an accurate correlation.